(a) Field
The subject matter disclosed generally relates to ceiling fans.
(b) Related Prior Art
FIG. 1 illustrates a conventional axial ceiling fan 20. The ceiling fan 20 includes a plurality of paddles 22, a lamp 24, a motor 26 for turning the paddles 22, and attachment means 28 for attaching the ceiling fan 20 to the roof.
This type of fans has several problems. One of the problems is the uneven distribution of air throughout the room. The paddles are mounted vertically to the axis of rotation and push the air downward in the same direction as the axis of rotation. Therefore, the area outside the radius of the paddles remains unventilated. Other problems associated with axial fans include the space occupied by the paddles and the safety concerns due to the fact that the paddles are exposed as they rotate.
Several attempts have been made to address this problem. For example U.S. Patent Publication No. 2007/0247854 describes a ceiling fan in which the paddles are covered by a casing as shown in FIG. 2. The solution described in this reference addresses only the safety concern. However, the space occupied is substantially the same or even greater than that of FIG. 1, and the lack of even distribution of air remains the same.
One way for reducing the size of the fan, is to make the paddles shorter. Thus, to obtain the same ventilation results, the rotation speed has to be increased, which results in an increase in energy consumption and noise.
Other attempts to address these problems are described in U.S. Pat. Nos. 1,699,201; 4,473,000; 4,768,424, 7,381,129 etc. These references address one problem on the expense of the other.
Therefore, there is a need for a ventilation system which is efficient, safe to use, quiet, and provides even distribution of air throughout the room especially when the air is heated.